1. Field of the Invention
The present invention relates to a method used in an image recognition unit, the method for avoiding an obstacle that prevents image recognition or an optical phenomenon that degrades image quality to provide high image quality.
2. Description of the Related Art
When a camera is used in bad weather, such as in the rain, or in a bad condition in which a large number of dusts are present, obstacles, such as water drops or dusts, may attach to a lens or a protective cover for the lens. It is important to remove such obstacles in order to provide a high-quality image, and there is a method for removing such obstacles, for example, using a wiper blade (see JP-A-6-303471). Although the method involves removing obstacles themselves and hence is effective, the fact that the wiper blade appears as another obstacle in an image renders the method unsuitable for high-quality-oriented imaging. The method causes other problems as well, including missing image information on the portion hidden behind the wiper blade and necessity to provide a mechanism for actuating the wiper and hence maintenance of the mechanism.
A method for applying a water-repellent agent or other agents onto a lens to remove water drops and dirt has been proposed (see JP-A-5-232566). In the method, however, such obstacles can be reduced in number, but cannot be removed entirely.
On the other hand, there is a method for removing obstacles, such as water drops, in a captured image by using a plurality of cameras to capture images and combining the images free from the influence of the obstacles. The method, however, requires significant equipment expense and installation space as well as a power supply and other devices for driving such an apparatus.
There is also a method for combining portions free of water drops or other obstacles by using a camera that can pan and tilt in horizontal and vertical directions and capturing images while the camera pans and tilts. However, as in the method described above, the method requires significant equipment expense and installation space as well as a power supply and other devices for driving such an apparatus. Further, the method cannot disadvantageously provide the resultant image free from influence of obstacles in real-time.
When an object to be imaged contains a high-intensity light source, an optical phenomenon called glare occurs. Glare is a phenomenon in which an object becomes less visible by a light source, and occurs in observation by human eyes and a camera.
To remove glare, one can wear sunglasses, polarized glasses, or anti-glare filters or use an expensive low-glare lens. These devices can reduce the influence of glare, but not sufficiently. There is still a need for further improvement.